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Open AcceResearch articleUse of an electromagnetic colonoscope to assess maneuvers associated with cecal intubationRussell I Heigh*†1, John K DiBaise†1, James A Prechel†1, Billie J Horn†1, Sarah San Miguel†1, Evelyn G Heigh†2, Jonathan A Leighton†1, Cynthia J Edgelow†1 and David E Fleischer†1

Address: 1Division of Gastroenterology, Mayo Clinic Arizona, 13400 East Shea Blvd, Scottsdale, Arizona 85259, USA and 2Department of Kinesiology, College Of Liberal Arts and Sciences, Arizona State University 300 East University Drive, Tempe, Arizona 85287, USA

Email: Russell I Heigh* - heigh.russell@mayo.edu; John K DiBaise - dibaise.john@mayo.edu; James A Prechel - prechel.james@mayo.edu; Billie J Horn - horn.billie@mayo.edu; Sarah San Miguel - sanmiguel.sarah@mayo.edu; Evelyn G Heigh - evelyn.heigh@asu.edu; Jonathan A Leighton - leighton.jonathan@mayo.edu; Cynthia J Edgelow - edgelow.cynthia@mayo.edu; David E Fleischer - fleischer.david@mayo.edu

* Corresponding author †Equal contributors

AbstractBackground: Safe and effective colonoscopy is aided by the use of endoscopic techniques and maneuvers(ETM) during the examination including patient repositioning, stiffening of the endoscope and abdominalpressure.

Aim: To better understand the use and value of ETM during colonoscopy by using a device that allowsreal-time imaging of the colonoscope insertion shaft.

Methods: The use of ETM during colonoscopy and their success was recorded. Experiencedcolonoscopists and endoscopy assistants used a commercially available electromagnetic (EM) transmitterand a special adult variable stiffness instrument with 12 embedded sensors to examine 46 patients. In 5 ofthese a special EM probe passed through the instrument channel of a standard pediatric variable stiffnesscolonoscope was used instead of the EM colonoscope.

Results: Thirty-nine men and 7 women with a mean age of 64 years (range 33–90) were studied. Thececum was intubated in 93.5% (43/46). The mean time to reach the cecum was 10.6 minutes (range 3–25).ETM were used a total of 174 times in 41 of the patients to assist with cecal intubation. When ETM wererequired to reach the cecum, and the cecum was intubated, an average of 3.82 ETM/patient was used.While ETM were used most often when the tip of the colonoscope was in the left side of the colon (rectum5.0%, sigmoid colon 20.7%, descending colon 5.0%, and splenic flexure 11.6%), when the instrument wasin the transverse colon (14.8%), hepatic flexure (20.7%) and ascending colon (19.8%) the use of ETM wasalso required. When the colonoscope tip was in the transverse colon, hepatic flexure and ascending colon,ETM success rates were less (61.1%, 52.0%, and 41.7% respectively) compared to the left colon successrates (rectum 83.3%, sigmoid colon 84.0%, descending colon 100%, and splenic flexure 85.7%).

Conclusion: The EM colonoscope allows imaging of the insertion shaft without fluoroscopy and is a usefuldevice for evaluating the efficacy of ETM. ETM are important tools of the colonoscopist and are used mostoften in the left colon where they are most effective.

Published: 9 April 2009

BMC Gastroenterology 2009, 9:24 doi:10.1186/1471-230X-9-24

Received: 2 September 2008Accepted: 9 April 2009

This article is available from: http://www.biomedcentral.com/1471-230X/9/24

© 2009 Heigh et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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BackgroundThe performance of safe and effective colonoscopy isaided by the use of endoscopic techniques and maneuvers(ETM) during the examination. Among the ETM com-monly used are patient repositioning, stiffening of thecolonoscope, and the application of abdominal pressure.The endoscopy unit at Mayo Clinic Arizona employs thesetechniques, teaches them to our trainees, endoscopy unitstaff and others interested in the performance of colonos-copy [1,2]. An inability to actually see the problem imped-ing forward advancement of the colonoscope (e.g.,looping, angulation) has limited the understanding of thebenefits and limitations of the ETM. The recent commer-cial availability of an electromagnetic colonoscope and anaccessory package was felt to be of potential use in thisregard. Initial reports of use of an electromagnetic colon-oscope sought to develop a means to view the instrumentshaft in real-time without the need for fluoroscopy [3,4].Electromagnetic coils to generate low strength magneticfields and detected by sensors in the colonoscope inser-tion shaft were used and the colonoscope position wasestimated based on a computer algorithm using triangula-tion principles. The prototype colonoscopes were subse-quently refined by incorporating enhanced computingtechniques to improve the accuracy, and refined computergraphics to improve usability [5]. In 2002, the OlympusCorporation introduced the first commercially-available,standardized electromagnetic colonoscope system. Theaim of our study was to use this commercially availableelectromagnetic colonoscope to better understand the useof ETM in terms of when and why needed, and the ulti-mate success in allowing forward advancement of thecolonoscope. This was done as part of a 6-week clinicalevaluation of the instrument and accessories in our rou-tine colonoscopy practice.

MethodsAn electromagnetic colonoscope that is United StatesFood and Drug Administration approved and availableworldwide was loaned to our endoscopy by the OlympusCorporation for use in our clinical practice between 9/14/2007 and 11/8/2007. Data about its use were collectedprospectively to determine how this instrument might fitin with, and possibly improve, our colonoscopy practice.The retrospective analysis of this data was approved by theMayo Clinic Institutional Review Board.

InstrumentAn electromagnetic (EM) transmitter and a special adultvariable stiffness instrument (outer diameter 13.2 mm,length 1680 mm, 140 degree view angle, and 3.7 mminstrument channel) with 12 embedded sensors(ScopeGuide (SG) Magnetic Endoscope Imaging System,CF-Q160DL, Olympus Corp. America, Center Valley,Pennsylvania) was used. The system consists of 2 main

components: 1) Electromagnetic coils that generate a lowlevel of energy are in a plate-like device positioned next tothe patient, and 2) 12 sensor coils are built into the colon-oscope shaft. A continuous real-time view of the colono-scope shaft is displayed both on a dedicated auxiliarymonitor and on the main endoscopy monitor as aninserted picture next to the endoscopic image. The imagescan be viewed in two planes: lateral or anterior-posterior.An accessory catheter probe device that has sensorsembedded in a cable that may be advanced through theworking channel of a standard colonoscope also accom-panies the system. The accessory catheter allows the shaftof any colonoscope to be visualized with this system.Additionally, an accessory marker sensor allows the posi-tion of the hands of an assistant providing abdominalpressure to be identified on the same screen.

PatientsThe ScopeGuide system was used when the endoscopistdetermined a patient was suitable for examination withan adult variable stiffness colonoscope. Patients with apacemaker or implantable defibrillator were excluded.The first patient of a half-day endoscopy session was stud-ied so that the regular endoscopic procedure schedulewould remain unaffected by the trial. The EM accessorycatheter probe was selected for use when the colono-scopist preferred to use a pediatric variable stiffness colon-oscope to examine a patient. The usual clinical practice ofthe 3 colonoscopists is to use a pediatric variable stiffnesscolonoscope in most women, and in about half of themen referred for colonoscopy.

Endoscopy TeamThree highly experienced colonoscopists (RIH, JKD, DEF)and three highly experienced endoscopy technicians (JAP,BJH, SSM) performed the examinations.

Endoscopic Techniques and ManeuversWhile the colonoscope was being inserted the endoscopynurse or observing endoscopy technical assistant recordedETM and its success or failure. Instrument stiffening,patient position change, external abdominal pressureapplication, reasons for application, and colonoscope tipposition during application were noted. When stiffeningof the colonoscope was utilized, the instrument wasadjusted from baseline minimum stiffness to maximumstiffness. Maneuver success was determined by the endo-scopist at time it was used and was defined as the abilityto further advance the colonoscope. Maneuver success orfailure was recorded during the examination.

ResultsPatient InformationA total of 46 patients were examined. Of these, 39 weremen. The age range was 33–90 years with a mean of 63.6

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years. The weight range was 52–110 kg with a mean of83.1 kg.

Colonoscopy InformationThe cecum was reached in 43/46 patients (93.5%). Thetime required to reach the cecum and achieve cecal intu-bation was 3–25 minutes with a mean of 10.6 minutes. Ofthe 46 patients examined, 41 were examined with the ded-icated electromagnetic colonoscope. In 5 patients the EMcatheter probe with sensors was used along with a stand-ard pediatric variable stiffness colonoscope. In these cases,the instrument shaft was imaged just as well as with thededicated adult colonoscope with the built-in sensors;however, the use of this probe was ultimately abandoneddue to its effect of limiting suction capability. All patientswere American Society of Anesthesiology class I or II func-tional status, and received intravenous midazolam andmeperidine or fentanyl under direction of the gastroenter-ologist to achieve moderate levels of sedation.

Endoscopic Techniques and ManeuversEndoscopic techniques and maneuvers (ETM) were usedduring colonoscopy in 89.1% (41/46 patients). For allpatients in the study, a total of 174 ETM were used. For thepatients where the cecum was reached (43 patients), atotal of 145 ETM were used, with a mean ETM per patientof 3.37 (145 ETM/43 patients). For the 38 patients whoactually required ETM for successful scope advancementto the cecum (5 reached cecum without ETM), the ETMper patient was 3.82 (145 ETM/38 patients).

The reasons for use of ETM are presented in Table 1. Themajority of the ETM were used when the colonoscope tipwas in left side of the colon. Rectosigmoid angulation, sig-moid colon loop formation, angulation of the sigmoidcolon, descending colon loop formation, splenic flexure

loop formation and angulation of the splenic flexureaccounted for 72.6% of reasons for ETM use.

The position of the colonoscope tip when ETM wererequired is presented in Table 2. While the colonoscopescope tip position was in the left colon or transverse colonthe majority of the time when ETM where applied 59.5%,the colonoscope tip was at the hepatic flexure or ascend-ing colon 40.5% of the time. Less success of ETM wasnoted when ETM were used when the colonoscope tip wasin the transverse colon (61.1%), hepatic flexure (52%)and ascending colon (41.7%) compared to elsewhere inthe colon.

The success of the various Endoscopic Techniques andManeuvers utilized (n = 174), is presented in Table 3.Patient repositioning, stiffening of the endoscope, andapplying abdominal pressure had success rates of 73.7%,69.2%, and 71.8% respectively. Figure 1 depicts theOlympus Scope Guide System. Figure 2 and Figure 3 dem-onstrate various views of the colonoscope in the cecumand the looping of the colonoscope.

DiscussionOur experience with a commercially available electromag-netic colonoscope demonstrates that the insertion shaft ofthe colonoscope can indeed be reliably visualized withoutthe need for fluoroscopy. This ability may shed light onthe effectiveness of individual endoscopic techniques andmaneuvers to facilitate cecal intubation and may improvethe teaching of colonoscopy to trainees and endoscopyassistants.

We have found that a commercially-available electromag-netic colonoscope can be used to reliably assess the posi-tion and location of the colonoscope during anexamination and may be useful to assess the efficacy of

Table 1: Indications for Endoscopic Techniques and Maneuvers

Rectosigmoid Angulation 3.3%

Sigmoid Loop 47.1%

Sigmoid Angulation 1.6%

Descending Loop 2.4%

Splenic Flex Loop 11.6%

Splenic Flex Angulation 6.6%

Transverse (Trans) Loop 9.0%

Hepatic Flex Angulation 9.9%

Unspecified 8.5%

Table 2: Position of the Colonoscope Tip and Success When Endoscopic Techniques and Maneuvers were Required

Frequency Success

Rectum 5.0% 83.3%

Sigmoid 20.7% 84.0%

Descending 5.0% 100.0%

Splenic Flex 11.6% 85.7%

Transverse Loop 14.8% 61.1%

Hepatic Flex 20.7% 52.0%

Ascending 19.8% 41.7%

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ETM. In the patients evaluated, 89.1% required the assist-ance of ETM to reach the cecum, and when successful, anaverage of 3.82 ETM per patient were required. The major-ity of the EMT were used because of colonoscope loopingwhen the colonoscope was in the left side of the colon;however, transverse colon looping and hepatic flexureangulations were also relatively common reasons for theneed to use these techniques. Of particular interest, whenthe colonoscope tip was in the transverse colon, hepaticflexure, and ascending colon, the success rates of ETMwere less than when in the left colon.

Visualization of the insertion shaft position has beenstudied by others with mixed results regarding its clinical

utility. In a study involving 100 patients in which a proto-type electromagnetic colonoscope was used, loopingoccurred in 91%; sigmoid looping (78%) and deep trans-verse looping (34%) were most common [6]. Interest-ingly, most loops were incorrectly diagnosed (position ortype) by the colonoscopist (69%) without use of theinformation gained from the imaging device. With regardsto ETM use, abdominal pressure was effective in produc-ing forward movement of the colonoscope only 54/154times (37%), whereas position change was effective 95/144 times (66%). Sigmoid pressure was ineffective due tohand misplacement in 36%, incorrect diagnosis of loop-ing or inaccessible looping in 52%. Transverse colon pres-sure was often unsuccessful due to under recognized or

Table 3: Frequency and Success of Different Endoscopic Techniques and Maneuvers (n = 174 ETMs)

Frequency Success

Patient Repositioning 28/38 73.7%

Stiffening of Endoscope 18/26 69.2%

Abdominal Pressure (Varied types & sites) 74/103 71.8%

Unspecified 4/7 57.1%

Scope Guide System, OlympusFigure 1Scope Guide System, Olympus.

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Colonoscope in CecumFigure 2Colonoscope in Cecum. Different patients (n = 8) with the electromagnetic colonoscope tip in the cecum. Patients A, B, and C are monitor views of full frame electromagnetic colonoscope images, with picture-in-picture endoscopic images. Patients D, E, F, G, and H are full frame monitor views of endoscope image with electromagnetic colonoscope picture-in-picture images. Various orientation and display options are depicted.

Colonoscope LoopingFigure 3Colonoscope Looping. Different patients (n = 8) with looping at various colon positions depicted on the electromagnetic colonoscope picture-in-picture insert.

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unappreciated sigmoid looping in 86%. In another studyof the use of the electromagnetic colonoscope involving78 patients, looping occurred in 33% of the cases and ledto the application of abdominal pressure and early posi-tion changes that assisted the completion of the examina-tion [7]. Importantly, the device was also found to beaccurate in estimating lesion location and was suggestedto be helpful in difficult examinations. More recently, in arelatively large study, patients undergoing unsedatedcolonoscopy were shown to have a significantly highercecal intubation rate when the EM scope was used com-pared to the same instrument with out EM shaft visualiza-tion (90% vs. 74%; P < 001) [8].

The EM colonoscope has also been used to study the util-ity of the variable stiffness colonoscope [9]. In 257patients studied, cecal intubation times were shorter andfewer ancillary maneuvers were required when a variablestiffness colonoscope was used. Maximal effectiveness ofthe variable stiffness colonoscope occurred when thedevice was stiffened after the sigmoid colon was negoti-ated and the colonoscope was straightened in the proxi-mal colon. These investigators went on to demonstratethat the EM scope allowed accurate loop assessment andscope straightening during colonoscopy, but did notresult in a reduction of sedation dosage during colonos-copy when the overall medication doses were small [10].

In contrast to the above reports, other studies have failedto show a clinical benefit of the electromagnetic colono-scope outside of a training setting [11]. In a 120 patientstudy involving experienced endoscopists, the electro-magnetic colonoscope offered no performance improve-ment. The only benefit noted was in localizing lesions andit was felt that the instrument was mainly of benefit inlocalizing small tumors before colorectal surgery. Theearly mixed evaluations of the use of an electromagneticcolonoscope prompted an editorialist to describe theinstrument as a "GPS Device for the Colon" in the sensethat expert navigators may never need help with direc-tions on well travelled routes; however, inexperienceddrivers may benefit from the use of a navigation system[12].

Although our study is limited by examining only a smalland select subset of our large colonoscopy practice(approximately 6,500 colonoscopies year), it is clear thatthe technology is able to accurately visualize the colono-scope configuration and positions, and may be of use inunderstanding ETM used in achieving cecal intubationduring colonoscopy.

ConclusionThe electromagnetic colonoscope can provide reliableinformation about the position of the colonoscope inser-

tion shaft and may be helpful in understanding the useful-ness of endoscopic maneuvers and techniques required toachieve cecal intubation. It is conceivable that with anappropriate study design, the instrument may be used tostudy when each specific ETM, either alone or in combi-nation, may assist cecal intubation. Furthermore, whilethe use of this instrument by experienced colonoscopistsmay not be necessary with sedated colonoscopy practice,it may have an application in unsedated colonoscopy andin training physicians to perform colonoscopy or alliedhealthcare members to assist in colonoscopy examina-tions. Additional uses of the electromagnetic colonoscopeand the technology behind it may emerge as the ability tovisualize the insertion shaft and scope tip without fluoros-copy becomes more widely recognized. For example, rap-idly evolving endoscopic techniques like enteroscopymight be enhanced by incorporating electromagneticimaging technology into endoscope design.

Competing interestsRIH: Previous research grant support from Olympus forstudy of video capsule small bowel imaging device, 2005–2006. JAL: Previous research grant support from Olympusfor study of video capsule small bowel imaging device,2005–2006. DEF: Previous research grant support fromOlympus for study of video capsule small bowel imagingdevice, 2005–2006. JKD, JAP, JBH, SSM, EGH, CGE: Nocompeting interests.

Authors' contributionsRIH, JAP, and DEF conceived the study, participated in itsdesign and coordination and helped draft the manuscript.JKD, BJH, SSM, JAL, and CGE participated in study designand helped draft the manuscript, EGH performed the dataanalysis, statistical analysis, and helped draft the manu-script. All authors read and approved the final manu-script.

AcknowledgementsWe thank the Olympus Corporation of America for providing the ScopeGuide System to our endoscopy unit on a loan basis.

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AbstractBackgroundAimMethodsResultsConclusion

BackgroundMethodsInstrumentPatientsEndoscopy TeamEndoscopic Techniques and Maneuvers

ResultsPatient InformationColonoscopy InformationEndoscopic Techniques and Maneuvers

DiscussionConclusionCompeting interestsAuthors' contributionsAcknowledgementsReferencesPre-publication history